SUPPLEMENTARY READING
(1) Geological maps
Maps Types of maps
Maps are one of the most important
media used to communicate
information in exploration geology.
Maps are a two dimensional
representation of the surface of the
earth and its features. Maps have two
main purposes: 1) to convey detailed
information about a specific area, and
2) to indicate the position of the
specific area relative to other parts of
the earth. The first is accomplished
by recording information in graphic
form. The second is accomplished by
showing reference marks (or a
coordinate system), or by showing a
small scale location map with well
known landmarks. A coordinate
system is nothing more than a
graphical means of locating any point
on the map, with two coordinates for
each point giving positions with
respect to the X axis and Y axis.
Most maps have more than just a map
area, they often have lots of other
information that is given in the space
around the main map area. A
complete map generally has several
main components. In addition to the
main map area, a complete map will
usually include the following
information in various positions
adjacent to the main map area: 1)
title, 2) author (s), 3) date, 4) scale, 5)
indication of true and magnetic north,
and 5) coordinates or reference
points, 5) explanation (code for
Many types of maps are used in
exploration geology. Topographic
maps are the most widely used maps.
These depict the surface morphology
by showing lines of equal elevation
(or contour lines). The most basic
and essential type of map used by
geologists is the geologic map. A
geologic map shows rock types (or
lithologies) and their geometry.
Geologic maps are very often
constructed on a topographic base
map.
Fig. 2. Geophysical Map
Other types of maps which are used
in conjunction with geologic maps:
(1) geophysical maps show readings
of magnetism, gravity, electrical
conductivity, radioactivity, or other
physical properties of rocks in an
area;
(2) geochemical maps show
geochemical values of samples